Is your garden overrun with Japanese beetles? Here’s how to get rid of Japanese beetles naturally before they destroy your favorite plants.
I’ve written before about some persistent garden nemeses, SWD fruitfly (destroyers of our precious Juneberry crop) and the heartbreaking squash vine borers. Every few years I meet another garden unfriendly and have to learn how to deal with them.
Japanese beetles are the latest bug to wreak havoc on my edible yard, and getting them under control is a top summer priority, along with battling the mosquitoes brought on by the excessive rainfall we’ve had. (Here’s the homemade bug repellant we use when they become a problem.)
Let’s explore how to get rid of Japanese beetles before they defoliate your favorite plants.
WHAT ARE JAPANESE BEETLES?
Japanese beetles, Popillia japonica, are an invasive scarab beetle introduced in the U.S. in the early twentieth century. As non-natives, they have no natural predators here (except frustrated gardeners), and their populations can get out of control.
Japanese beetles are typically about a half-inch long and have iridescent copper-colored backs and green heads.
Their larvae, known as grubs, live in the soil until they mature, feeding on the roots of plants. They’re notorious wreckers of lawns in this immature stage, and when they emerge as adults, they set off in search of more delectable plants to chew to smithereens.
WHAT DO JAPANESE BEETLES DO TO PLANTS?
They say a picture’s worth a thousand words, so to save you some time, here’s a shot of one these buggers having an afternoon snack of my grape leaves.
You can imagine what it looks like when hundreds of them have done this to hundreds of leaves on a vine or a tree. The photo above doesn’t do justice to how terrible they can make plants look, leaving nothing but the skeletons of every leaf they attack.
My state’s extension says that the damage is mainly cosmetic, but if you have a huge wall of grapevines that the stinkers have skeletonized, it’s not only unsightly, but the leaves also can’t serve their purpose of providing cooling shade.
If you’re a fan of roses and they destroy the flower, then that kind of defeats the purpose of growing them, right? In some cases, Japanese beetles also eat fruit.
Some people have reported that extremely large infestations, which defoliate a plant or tree completely, may wind up killing the plant.
Japanese beetle feeding season is only about 6 weeks, but they can do an astonishing amount of damage in a very short time if their numbers are great enough.
Unfortunately, my edible landscape — built over time using shortcut permaculture principles — has many plants that Japanese beetles find utterly irresistible. Their current favorite seems to be my beloved grapevines, which shade our porch from summer heat and screen us from the view of passersby.
In addition to the grapes themselves, grape leaves are edible. (Recipes coming soon!)
They’ve also gone after our plum trees, greedy little pests.
These little buggers are determined to shred our grape leaves to confetti. We’re fighting back with several of these methods for Japanese beetle control.
If you have a lawn that’s been attacked by grubs (beetle larvae), you’ll want to know how to control Japanese beetles as well.
Though you might consider ditching your lawn, which is a great environmental move anyhow. Here’s why to choose alternatives to grass.
HOW TO GET RID OF JAPANESE BEETLES NATURALLY
We’re all about natural here at HealthyGreenSavvy. Who wants dangerous chemicals in their garden?
Fortunately, there are ways to deal with Japanese beetles without resorting to harmful pesticides.
I generally have a live-and-let-live attitude in the garden. I don’t worry too much about weeds — so many of them are edible, anyhow — or the various bugs who call our yard home unless they upset the balance in the yard.
Then I get serious. Even vengeful. You’ll see what I mean as we go over how to get rid of Japanese beetles.
It’s too bad, because Japanese beetles are kind of gorgeous. Their metallic bronze and green colors are quite stunning. But allowing some to remain means inviting a full-blown destructive infestation, because their presence attracts boatloads of their buddies to the feast they found. Until every single leaf is nothing but a skeleton, and they move on to their next victim.
The most critical thing in your battle against these critters is EARLY intervention. If you get rid of any Japanese beetles you find early on, they won’t have a chance to invite all their friends to join them or reproduce, so you may avoid a full-blown infestation.
I’ve read the leaves they destroy send off extra scent to tell other Japanese beetles in the area where the good eating is, so the longer you allow them to nibble your plants, the more you’re inviting to the feast.
So keep your eyes peeled for damage and GET THEM as soon as you notice they’re there. The first year I found them on my grapevines, I had no idea what I was in for till it was too late.
And they multiply quickly. One day you don’t see them at all and the next you may find hundreds. Be vigilant if you’ve seen them in your garden, as it’s so much easier to deal with them when there are only a handful.
NATURAL CONTROL OF JAPANESE BEETLES: PREVENTION STRATEGIES
Preventing an infestation from happening in the first place will save you time and aggravation. Here are some things to do to keep populations down before they have a chance to explode.
1. MANAGE YOUR GARDEN
Japanese beetles will be attracted by any rotting plants or overripe fruit, so removing them promptly will help keep your garden from smelling so tempting.
–> Note that if you’re dealing with other pest issues, like squash vine borer or SWD, you need to throw any infected plant material in the trash rather than the compost, or you’ll just perpetuate the problem. I know, it’s hard to toss valuable plant matter in the garbage can instead of your compost pile, but in this case it’s for the good of your garden.
2. GO AFTER GRUBS IN THE SOIL
Your Japanese beetle population will be greatly reduced if you get rid of the larvae before they can destroy your garden.
Japanese beetle larvae can be driven out of the soil in fall and spring by a weekly soaking with soapy water. Birds will come eat the surfaced grubs, helping to keep your Japanese beetle population down.
Bacillus popilliae, also known as milky spore, is a bacteria that causes disease in Japanese beetle grubs, though it isn’t harmful to other animals or humans. It’s sold as a treatment for grubs, but university research trials have not found it especially effective. Reviewers on Amazon, however, report success if you want to give it a try.
Letting your lawn go dormant in summer rather than watering it will not only save a lot of water, it will keep your grub population from exploding.
3. WELCOME PREDATORS
Some birds apparently eat Japanese beetles, including robins, crows, cardinals and bluejays. We have some of these in our yard, but an infestation is too big to be controlled by our resident feathered friends. I’ve read raising ducks, guinea fowl, or chickens, which might actively prey on Japanese beetles, can help.
Tachinid flies are another predator of the Japanese beetle, and the University of Maryland suggests incorporating plants that attract them could help keep Japanese beetles under control. Tachnid flies may help with other pests as well.
Tachinid flies like plants with umbels of flat florets, including carrots, Queen Anne’s lace, cilantro, dill, buckwheat, clover, asters, daisies, and anise hyssop. If you have a shadier garden, a number of these plants are herbs that grow in shade.
Though it’s not mentioned in the sources I consulted, elderflowers have flat umbels that tachinid flies should as well, and there are SO many reasons to add elderberry plants to your garden!
Many of these favored plants have edible flowers you can enjoy as well, and they’ll attract pollinators and other beneficial insects.
Beneficial nematodes go after the larvae and may help keep populations of Japanese beetles as well as a number of other pests down. Here’s more on the different kinds of nematodes to consider from the University of Vermont. H. bacteriophora the type that goes after Japanese beetle grubs.
Nematodes are most effective when added to your soil in late summer and early fall, which will lower populations the following year. However, nematodes can be added to the soil anytime, as long as you keep your soil watered.
4. GROW PLANTS THAT REPEL JAPANESE BEETLES
Unfortunately Japanese beetles like some of the same plants we most value in our edible gardens, including beans, plums and apple trees, and grapevines. They’re also partial to roses, hibiscus, maple, linden, and birch.
Choosing plants that repel Japanese beetles may help keep them away from plants you want to protect. Some options to consider:
Perhaps my catnip, garlic, and chives help to some extent, but they’re not in great enough numbers near my grapevines to overcome Japanese beetles’ determination to eat every leaf in sight.
Growing plants that Japanese beetles don’t tend to eat may also reduce your yard’s attractiveness to beetles. They don’t generally like plants with fuzzy or textured leaves. Below are some possibilities:
- Shagbark hickory
- Tulip tree
I’ve seen elderberry listed as a plant they don’t like, but Japanese beetles also come up in lists of pests that go after elderberry. I wouldn’t count on elderberry if you’re looking to beetle-proof your yard, but they’re worth growing anyway, for their medicinal flowers and berries. (Here’s more on the health benefits of elderberries.) They shouldn’t attract Japanese beetles the way grapes and roses do.
Geraniums are appealing to Japanese beetles, but a compound in geranium flowers makes them dizzy, so they fall to the ground and are more open to predators (which can include you if you’re so inclined).
Another plant, Mirabilis jalapa (also called 4 o’clocks), apparently lures Japanese beetles with its fragrant flowers but contains toxins in its leaves that kill them. If you live in zones 7-10, 4 o’clocks will grow as perennials. In colder climates, you have to dig up the tubers and bring them in for the winter.
NATURAL CONTROL OF JAPANESE BEETLES: HOW TO DEAL WITH AN INFESTATION
If you already have a Japanese beetle infestation, here are some ways to handle it before your garden gets chewed to bits.
1. GET RID OF JAPANESE BEETLES BY DROWNING THE BUGGERS
The simplest way to get rid of Japanese beetles is hand-picking them off the plant and into a container of soapy water, where they will quickly drown. The soap provides surface tension that keeps them from getting out.
Besides being less disgusting than crushing them, you also avoid attracting more beetles, as smushed beetles emit pheromones that draw in more Japanese beetles.
The best time of day to get them is in the morning, when they’re reported to be more sluggish and the dew on their wings makes flying more difficult. I’ve had success in the evening as well, but they’re more prone to fly off. But truthfully, the best time to get them is any time you can. Do it when it works for you, as not doing it means allowing the beetles to win.
Though it may sound a little heartless, drowning Japanese beetles doesn’t take a strong stomach. They’re pretty slow and are easy to knock into your container, especially as they often seem to be busy mating. I take extra pleasure in drowning them as they try to multiply their forces of destruction.
If you’re more soft-hearted than I am, check out the other Japanese beetle control options below.
I try to get out twice a day to check the vines and the adjacent plum tree for more beetles. I spend maybe 5 minutes drowning all the ones I can reach, and typically there are about as many hiding out where I can’t. Where I can get in with a ladder I’ll try to take them out as well.
The drowning method is not a huge investment of time, but it takes some commitment as you likely can’t get all of them in one go. Plan to inspect your affected area at least once a day until you stop seeing them.
Tip: Some Japanese beetles will invariably land on you and scare the bejeezus out of you sometime later when you discover them crawling on your head or down your shirt. Brush yourself off well before going inside.
After they’ve died, you can dump them out of your container. Be wary of leaving them in the container too long, as you will find they stink something awful. (Yep, done that. Oops.)
2. NATURAL SPRAYS FOR CONTROLLING JAPANESE BEETLES
Soap and Water (with or without repellents)
Some gardeners have found a mixture of soap and water sprayed on beetles helps control them. Some people add vegetable oil or cedar oil, while others scent their spray with garlic or cayenne to make their plants smell bad to beetles.
I’ve also seen suggestions to use baby powder or baby oil, but I don’t recommend either of these in the organic garden. They smell bad to Japanese beetles, but they’re also full of harmful chemicals that have no place in an edible landscape.
Neem oil is the pressed oil of the fruits and seeds of the neem tree, and is often used in organic pest control and body care products. Neem interferes with beetles’ reproductive cycle, preventing eggs from hatching more beetles. Together with drowning adults, a neem spray should help reduce Japanese beetle populations if used every few days. You can buy neem oil here. You only use a little at a time, so a small jug should last a good long while.
Kaolin clay is a popular mineral-based product that can be sprayed on leaves and fruits to deter a number of pests in addition to Japanese beetles. You can find it here.
OTHER JAPANESE BEETLE CONTROL OPTIONS
COVER YOUR PLANTS
A simple row cover can keep Japanese beetles from getting access to your plants, though this doesn’t work in all cases. Our grapevines go up a good ten feet and stretch the length of the porch, so covering them isn’t practical. Even a mature dwarf fruit tree is too tall to cover.
Roses and raspberries might lend themselves more to the covering method.
If pollination is an issue, covering your plants may keep pollinators out as well and thus inhibit their ability to produce fruit, so bear that in mind as you consider your options.
WHAT ABOUT TRAPS FOR JAPANESE BEETLES?
My local extension does not recommend using commercial traps to catch Japanese beetles, as the lures they use reportedly attract more beetles to your yard than will get caught in your trap. You want to make your infestation better, not worse.
However, thinning out the population in your area might be seen as a beneficial service to society, so have at it and see what you think. Just place the trap well away from the plants you’re trying to protect. Here are some options.
Several online sources recommend a homemade trap made from fermented fruit cocktail. I’m not sure why you would need to buy canned fruit. I’m going to try it with some fruit scraps and see what happens.
They recommend letting the fruit cocktail ferment in the sun for a few days and then put it on some bricks inside a bucket. You then fill the bucket just up to the level of your can of fermented fruit and place it about 25 feet from the plants the beetles are after. The beetles apparently drown on their way to get the fruit.
If you try it, let me know if it works!
Another source suggested fermenting a ripe banana and yeast in a gallon milk jug, which seems potentially easier than bricks in a bucket. Yeast is in such short supply these days, I’m going to try just the banana and see how it does. I had some overripe bananas I was slicing up for banana ice cream and put the bruised parts I cut off into an empty milk jug. I’ll update the post when I have results to share.
One other suggestion I found in my extensive snoops online about how to get rid of Japanese beetles: Vacuum them! I’m not sure how you avoid sucking in the whole leaf, but if it works for you, let us know.
How do you get rid of Japanese beetles? Please leave your suggestions in the comments. (Or feel free to just vent!)
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